As a matter of fact, I work in a company with a close equivalent: due to the worker-friendly labor laws and a very powerful union, if a worker stays with the company for three years, firing him costs the company a years' salary (unless gross misconduct is demonstrated), thus giving high-salary positions (like programmers) an equivalent to tenure.
On the other hand, programmers are rarely/never advanced, there's no career plan.
As you suspect, it discourages studying and promotes laziness and getting out of date with current programming pratices.
And it also raises a tough mental barrier to exit, I'm unhappy here, but I really like having a safety net and have high fixed expenses and there's no unemployment in my country if I quit voluntarily, so I'm reluctant to quit unless I make my nest egg, which I've been putting off for some time.
Back to teachers, if there are no incentives, I suspect it might make them less motivated to stay up to date and better themselves - of course there are always those that are internally motivated and will do so whatever the environment, but many will be discouraged by it.